Order Publications

Reference: ISH2015_260

Type:ISH Collection

Title:

THE DISTRIBUTION OF TRAPPED CHARGES IN LDPE AND HDPE BY ISOTHERMAL POTENTIAL DECAY METHOD

Abstracts

Charactering the distribution of trapped charges and analysis the root causes of the traps within polyethylene is of great significance to control the space charge accumulation and improve the safe and reliable operation of the dc cables. In this paper, the distribution of trapped charges in low density polyethylene (LDPE) and high density polyethylene (HDPE) were investigated based on isothermal surface potential decay (ISPD) method. A non-contact setup was established to conduct corona charging measurement, by which the decay characteristics of the films with varied charging polarity can be obtained. The trapped charge distribution of LDPE and HDPE was obtained by a proposed model. The effects of morphological characteristics of LDPE and HDPE were further analyzed. It is shown that there are mainly deep trapped charges in LDPE and HDPE both for electrons and holes. The mean trap depth of holes is lower than that of electrons in LDPE, whereas it is reversed in HDPE. Furthermore, more trapped charges are accumulated in HDPE with deeper trap depth than that of LDPE. It is indicated that the obtained results may imply essentially nature of hole/electron traps, i.e., the electron-type traps show an inter-chain character whereas the character of hole-type traps is intra-chain. And it is implied that the trap distribution is further related to unique aggregation structure of LDPE and HDPE.